Applications in the millimeter-wave frequency regime have gained significant interest in the past few years due to the rapid advancement in low cost semiconductor technologies such as silicon germanium (SiGe) and fine geometry complementary metal-oxide semiconductor (CMOS) processes. Availability of high speed bipolar and metal-oxide semiconductor (MOS) transistors has led to a growing demand for integrated circuits for mm-wave applications at 60 GHz, 77 GHz, and 80 GHz and also beyond 100 GHz. Such applications include, for example, automotive radar and multi-gigabit communication systems.
As the operating frequencies of RF systems continue to increase, however, the generation of signals at such high frequencies poses a number of major challenges. One such challenge in the interfacing of millimeter wave signals to and from integrated circuits. At high frequencies, bond wires, package contacts, printed circuit board (PCB) traces, board capacitance, and other parasitics may potentially cause attenuation and mismatch of high frequency RF signals. In some systems, such as automotive radar systems, circuit boards interface with a high-frequency radar antenna using a waveguide in order to prevent signal losses.
In higher power millimeter wave systems, additional issues may arise with respect to thermal management. For example, circuit components configured to deal with high power may have wider conductive layers to withstand high currents and thermal dissipation structures such as vias in order to conduct heat away from a high power part. These conductive layers and thermal dissipation structures may increase parasitic capacitances and inductances that may degrade RF performance.